The procedure, calling “enteral feeding” is being used for 27 of 30 detainees on hunger strike at the US jail in Guantanamo Bay, according to the latest tally from prison authorities Friday.

The inmates’ hunger strike began six months ago as a protest against their continued incarceration without charge or trial for more than a decade. At the height of the protest 106 prisoners were on hunger strike, with 56 being fed by tube.

Authorities say the enteral feeding is merely “uncomfortable” and necessary to keep the protesters alive, and say they always offer a meal or a nutritional drink first.

Conteris began his strike two months ago in solidarity.

“President (Barack) Obama, stop the torture, you have the power. You don’t have to wait for the Congress, you’re the commander in chief,” he said.

“This White House is a blight house, because it conducts torture on a daily basis,” the activist said, gesturing toward the presidential office and residence behind him.

Conteris, who has lost nearly 49 pounds (22 kilograms) since beginning his strike, called on the 50 or so protesters surrounding him to “escalate your resistance, pressure President Obama” to “put an end to this madness.”

The doctor who inserted the tube, as well as a nurse from “Nurses against Torture,” said the tube they used was half the width of the one used at Guantanamo. However, the one military authorities showed AFP during a recent tour was far smaller than the one used on Conteris.

Before the protest, Conteris said it was “time to make visible the torture that happens in the shadows.”

“Let them die, President Obama, or free them,” he insisted.

Three of the 164 men still held at Guantanamo have filed a lawsuit against the force-feeding in federal court and are asking an appeals court to ban the procedure, calling it torture.

A federal judge earlier ruled the practice was “painful, humiliating and degrading” and should be stopped, but said she did not have jurisdiction to put it to an end.